Functionalization of microcrystalline cellulose (MCC) with 1,2,3,4-butanetetracarboxylic acid dianhydride (BTCAD) was obtained by esterification reaction. A novel macromolecule cross-linker, MCC-BTCAD-NHS (MBN), was successful prepared through amidation between N-hydroxysuccinimide (NHS) and MCC-BTCAD to modify gelatin films. The reaction between gelatin and MBN was confirmed by the residual free amino test, FTIR, elemental analysis, and XRD spectra. The results indicated that the addition of MBN into gelatin decreased the film degradation ratio and increased its thermal stability, flexibility, hydrophobicity, light barrier performance, and water adsorption ability. In addition, SEM images further proved the successful cross-linking reaction. The particular gelatin film material with excellent performance ended up the limitation of blending modification method for gelatin with natural macromolecule and extended its application in many fields.